From: Ciaran Woodward <ciaranwoodward@xmos.com>
To: Simon Marchi <simark@simark.ca>,
"gdb-patches@sourceware.org" <gdb-patches@sourceware.org>
Subject: RE: [PATCH] gdb: Fix missing first breakpoint in schedule-multiple mode
Date: Tue, 26 Jul 2022 13:16:43 +0000 [thread overview]
Message-ID: <DB9PR09MB4988AB824E4A1ACB991604FCB9949@DB9PR09MB4988.eurprd09.prod.outlook.com> (raw)
In-Reply-To: <7663ddf6-82f7-5d4f-836a-e0a93daa0f2b@simark.ca>
> Can you please provide some reproducing steps? Some simple test
> programs along with the sequence of GDB commands to use. This way, we'll
> be sure we look at the same problem.
Hi Simon,
Sure! The way I actually found this was when connected to a stub which
supports the multi process extensions of the remote serial protocol.
I managed to reproduce it using gdbserver on a linux system, but the
procedure is a bit more obscure:
In the case of the stub I am using, the 'processes' are actually hardware
cores, and so they already exist when you first connect to the remote.
In this reproduction, I run gdb twice - once to set up the remote state,
then a second time to connect to multiple processes at the same time, which
is what produces the issue. There may well be a simpler way to do this.
The program to reproduce is simple:
// run.c ---------------
#include <unistd.h>
#include <stdio.h>
int main(int argc, char *argv[])
{
printf("1\n");
sleep(2);
printf("2\n");
sleep(2);
printf("3\n");
while (1)
{
sleep(1);
printf(".");
}
}
// end run.c -------------
And I compiled it simply with: gcc -g run.c
Then to reproduce:
Run: gdbserver --multi :2331
# leave this running
Run: gdb
target extended-remote :2331
set schedule-multiple off
add-inferior
set remote exec-file ~/test/a.out
file ~/test/a.out
start
infe 2
file ~/test/a.out
start
disconnect
q
# now we have exited this instance of gdb
# gdbserver is still running, with 2 frozen processes
Run: gdb
target extended-remote :2331
# At this point, gdb has recognised both inferiors,
# but only sets the control->stop_soon field to STOP_QUIETLY_REMOTE
# on inferior 2. (which may also be a bug - maybe should be both)
set schedule-multiple on
infe 2
file ~/test/a.out
infe 1
file ~/test/a.out
break run.c:7
break run.c:10
dis 1.2
dis 2.1
c
# At this point, GDB sets the control->stop_soon field to NO_STOP_QUIETLY
# but only on the currently selected inferior (1).
# first breakpoint hit, inferior 1
c
# second break never hit, Ctrl-c also doesn't stop.
Cheers,
Ciaran
next prev parent reply other threads:[~2022-07-26 13:16 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-25 16:22 Ciaran Woodward
2022-07-25 17:02 ` Simon Marchi
2022-07-26 13:16 ` Ciaran Woodward [this message]
2022-08-09 15:00 ` [PING] " Ciaran Woodward
2022-08-23 16:30 ` [PING 2][PATCH] " Ciaran Woodward
2022-08-31 10:11 ` [PING 3][PATCH] " Ciaran Woodward
2022-09-22 13:22 ` [PING 4][PATCH] " Ciaran Woodward
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